Coordinated multi-point (CoMP) transmission and reception is considered for Long Term Evolution-Advanced (LTE-A) as the solution to improve the coverage of high data rate, the cell-edge throughput and/or to increase system throughput. In coordinated multi-point (CoMP) transmission, transmissions from multiple transmitter are made simultaneously to a single receiver. Coordination of the multiple transmissions made by the multiple transmitters enable the receiver to combine the transmissions to improve data rate coverage and to increase system throughput in advanced wireless communications systems, such as Long Term Evolution-Advanced (LTE-A).
In the uplink (UL) direction, a mobile station (MS) transmits data to a base station (BS). Uplink coordinated multi-point reception implies reception of the MS's transmitted signals at multiple geographically separated or co-located points e.g. a single MS transmitting to multiple BSs. BS is also commonly referred to as base transceiver station, controller, evolved NodeB (eNB), access point (AP), access network (AN), and so forth, while a BS may also be commonly referred to as user equipment (UE), access terminal (AT), subscribers, subscriber stations, terminals, mobile stations, and so on.
In the downlink (DL) direction where the BS transmits data to the MS, downlink coordinated multi-point transmission implies dynamic coordination among multiple geographically separated transmission points. Examples of downlink coordinated transmission schemes include coordinated beamforming where the data to a single MS is instantaneously transmitted from one of the transmission points and the scheduling decisions are coordinated to control e.g. the interference generated in a set of coordinated cells. In coordinated scheduling and coordinated beamforming, the data may only be available at a serving BS and transmission scheduling is coordinated among BSs within the CoMP cooperating set.
Joint processing/transmission is another example of downlink coordinated transmission scheme with more advanced interference mitigation capability where the data to a single MS is simultaneously transmitted from multiple transmission points, e.g. to (coherently or non-coherently) improve the received signal quality and/or cancel actively interference for other MSs. Downlink coordinated multi-point transmission includes the possibility of coordination between different cells. From a radio-interface perspective, there is no difference from the MS perspective if the cells belong to the same BS or different BS. If inter-BS coordination is supported, information needs to be signaled between BS.
In joint processing, there is an assumption that data is available at each transmission point (BS) in a CoMP cooperating set representing BSs participating in the CoMP transmission. The data may be transmitted from more than one BS at a time with dynamic BS selection when the data is transmitted.